Those skilled in the art will, of course, appreciate that a typical centrifugal pump includes a vaned impeller which is disposed within a suitable enclosed housing and cooperatively arranged on one end of a rotatable driving shaft that is coupled to a prime mover such as an electric motor located outside of the pump housing. The mid-portion of the shaft is extended through an opening in the pump housing and cooperatively journalled in a bearing assembly that is either mounted in the opening or in a separate housing immediately adjacent thereto. Inasmuch as the interior of the pump housing will be at an elevated pressure, a typical centrifugal pump also includes shaft-sealing means such as a so-called "stuffing box" or "packing gland" that is arranged around the opening in the pump housing and provided with one or more annular sealing members that are cooperatively engaged with the mid-portion of the shaft for hopefully preventing leakage of the pressured fluid around the rotating shaft.
Sooner or later such shaft seals will deteriorate, if not fail altogether; and, when this occurs, a highly-pressured leaking fluid will be discharged with considerable force through the clearance space around the rotating shaft. Ordinarily this will allow the leaking fluid to enter an outboard bearing as well as to contact the prime mover driving the pump. The severity of any damage caused by leakage such as this will, of course, be determined by the chemical nature of the leaking fluid. Thus, if the fluid is a corrosive substance such as an acid, a caustic or salt water, nearby equipment such as the prime mover or outboard bearings may be severely damaged or ruined unless the leakage is controlled. It will be recognized that in many instances, the replacement of the faulty sealing member will require the removal of the prime mover to gain access to the stuffing box. Thus, in addition to the time lost while the pump is out of service, even a simple replacement operation will entail considerable expense as well as require the services of skilled workmen should heavy-duty equipment be required to remove the prime mover.
Accordingly, in many situations, the common practice is to tolerate a limited amount of leakage though the packing gland and to minimize the leakage as long as it is reasonably possible by periodically tightening the packing gland. Thus, to minimize the damage that would otherwise be caused by leaking fluids, it has been a common practice heretofore to mount a flat disc or socalled "slinger ring" or "slinger" at some convenient location on the pump shaft between the pump packing gland and an outboard bearing assembly or the prime mover for the pump. In this way, as fluids leaking through the packing gland move longitudinally along the rotating shaft, they will be blocked by the slinger; and, by virtue of centrifugal force, once the fluids reach the slinger they will be slung radially outwardly in a transverse plane that lies substantially perpendicular to the axis of the pump shaft. As depicted in U.S. Pat. No. 2,248,505, for example, a slinger may also be retained on the pump shaft by a resilient collar which is tightly engaged over the shaft to block leakage past the collar as well as to facilitate the installation and removal of the slinger.
In most instances it has been found that a simple disc-like slinger is incapable of handling a large quantity of fluids leaking from a packing gland. For example, as disclosed in U.S. Pat. No. 4,181,312, a slinger ring may be shaped to define a plurality of outwardly-converging radial vanes that are separated from one another by a corresponding number of flat surfaces which are arranged to direct leaking fluids outwardly along the edges of the vanes toward the tips of the vanes and thereby concentrate the fluids near the rim of the disc where they are then propelled radially outwardly by the vanes. As described in that patent, unless that slinger ring is positioned immediately adjacent to the outboard bearing housing or prime mover being protected, a strong spray of leakage fluids can still pass over the rim of the slinger and strike the bearing or prime mover. As described in French Pat. No. 653,743, issued to Dujardia & Co. and published on Mar. 12, 1929, another type of slinger considered heretofore is shaped like a shallow circular saucer having an uninterrupted concave surface. This saucer-like slinger is mounted on a pump shaft between the pump and its prime mover so that the concave surface of the slinger is facing the shaft packing gland of the pump. In this manner, should there be a leakage of pressured fluids from the packing gland the fluids will strike the concave surface and be diverted outwardly and away from the prime mover.